Plastically deformable materials based on hollow metal balls are already known. Such materials are currently in demand for their numerous physical properties (robustness, light weight, impact resistance, etc.). Therefore, they are used in multiple applications, including in mechanical energy absorption devices (such as set forth in the article “Modelling of MHS cellular solid in large strains” published in International Journal of Mechanical Sciences Vol. 48 (2006) p. 1273-1286 or also in the article “Uniaxial Elasto-Plastic Behaviour of Adhesively Bonded Hollow Spheres Structures (HSS): Numerical Simulations and Experiments” in volumes 539-543 of Materials Science Forum (2007) p. 1874-1879). Such devices are for example used in the field of aeronautic, naval, automotive building, etc.
In FR 2,585,445 a method is more specifically described for making a cellular material item in the form of a compact arrangement of hollow metal balls. To this end, an appropriate amount of hollow metal balls is introduced into a mould having the shape of the desired item, then the balls are made integral in contact together.
Furthermore, FR 2,615,787 describes a method for manufacturing items made of a cellular material based on webs of hollow metal balls. According to such a method, ball webs are arranged in a mould so as to match the shape thereof. As soon as the mould is loaded with ball webs, the contacted balls are fastened to each other.
Thus, implementing the methods known from FR 2,585,455 and FR 2,615,787 absolutely requires using a mould for accommodating either balls, or ball webs.
Obviously, using even a mould is restricting, since it is required to manufacture it, and generally to remove it after the desired item has been obtained. In addition, only full cellular material items can be obtained through such known methods, since manufacturing hollow or recessed items cannot be contemplated or only with great difficulty.